Heat Pump Frozen Outside?

A light coat of frost on your outdoor heat pump on a cold Tampa morning is normal. The unit is pulling heat out of the air, and condensation freezes on the coil. A healthy heat pump runs a defrost cycle every 30 to 90 minutes and melts that frost off in 5 to 15 minutes. The problem is when the whole unit turns into a solid block of ice that does not clear, or when ice keeps coming back all day. In our experience across Hillsborough and Pinellas, here are the causes ranked by how often we find them.

1. Stuck or failed defrost control board. This is the number one cause we find. The board is supposed to trigger the defrost cycle on a timer plus a coil-temperature reading. When it fails, the unit just keeps running in heat mode and ices over completely.
2. Bad defrost sensor or thermostat on the coil. A cheap part that tells the board how cold the coil is. When it reads wrong, defrost never fires.
3. Low refrigerant from a leak. Low charge drops coil temperature below normal and frost builds faster than defrost can clear it. Common on units 8-plus years old where joints corrode in our humidity.
4. Dirty outdoor coil or blocked airflow. Oak leaves, lawn clippings, and dryer-vent lint pack into the coil fins and trap moisture against the cold metal.
5. Failed outdoor fan motor. If the fan is not spinning, air does not move across the coil and ice forms within an hour.
6. Reversing valve stuck. The valve that switches the system between heating and cooling can stick, leaving the unit unable to run a proper defrost.
7. Drainage pooling and refreezing. Defrost water that cannot drain off the pad pools under the unit and freezes back up overnight.

Cost depends entirely on which part failed. Here is where Tampa Bay pricing typically lands in 2026, with FREE diagnosis on every call so you only pay if you approve the repair.

• Defrost control board replacement: $295 to $595 installed, parts and labor. Most jobs done in under an hour.
• Defrost sensor or coil thermostat: $195 to $375 installed.
• Outdoor fan motor plus capacitor: $445 to $750 installed depending on motor type and brand.
• Refrigerant leak search and repair: $495 to $1,495 depending on leak location. A Schrader valve is the low end, a leaking coil is the high end.
• Reversing valve replacement: $650 to $1,350. On an older system this is often the point where replacement makes more sense than repair.
• Full heat pump replacement when the system is 12-plus years old: $7,500 to $12,500 for a properly sized Goodman or Daikin heat pump, including a load calculation and proper commissioning.

FREE estimates and FREE diagnosis on every visit. No diagnostic fee whether we do the work or not. We will quote every option that fixes the problem, not just the most expensive one.